Asp.net mailing process

this is madhava ,i want some help ,i am developing one website in that i implement mailing system process like gmail,

i faced some problem i.e is when sending a mail from asp.net to gmail it s working ,but when i enterd  wrong mail id and send i will be sent ,in that how can i get wrong mail id information to my asp.net webpage inbox(gridview).

Please any body give the suggestions.

Thanku & Regards

Madhava

madhup220@gmail.com